Biallelic and monoallelic pathogenic variants in CYP24A1 and SLC34A1 genes cause idiopathic infantile hypercalcemia

OBJECTIVE

Idiopathic infantile hypercalcemia (IIH) is a rare disorder of PTH-independent hypercalcemia. CYP24A1 and SLC34A1 gene mutations cause two forms of hereditary IIH. In this study, the clinical manifestations and molecular aspects of six new Chinese patients were investigated.

METHODS

The clinical manifestations and laboratory study of six patients with idiopathic infantile hypercalcemia were analyzed retrospectively.

RESULTS

Five of the patients were diagnosed with hypercalcemia, hypercalciuria, and bilateral medullary nephrocalcinosis. Their clinical symptoms and biochemical abnormalities improved after treatment. One patient presented at age 11 years old with arterial hypertension, hypercalciuria and nephrocalcinosis, but normal serum calcium. Gene analysis showed that two patients had compound heterozygous mutations of CYP24A1, one patient had a monoallelic CYP24A1 variant, and three patients had a monoallelic SLC34A1 variant. Four novel CYP24A1 variants (c.116G > C, c.287T > A, c.476G > A and c.1349T > C) and three novel SLC34A1 variants (c.1322 A > G, c.1697_1698insT and c.1726T > C) were found in these patients.

CONCLUSIONS

A monoallelic variant of CYP24A1 or SLC34A1 gene contributes to symptomatic hypercalcemia, hypercalciuria and nephrocalcinosis. Manifestations of IIH vary with onset age. Hypercalcemia may not necessarily present after infancy and IIH should be considered in patients with nephrolithiasis either in older children or adults.

A novel non-invasive identification of genome editing mutants from insect exuviae

With the wide application of genome editing in insects, a simple and efficient identification method is urgently needed to meet the increasing demand for mutation detection. Here, taking migratory locusts as a model system, we developed a non-invasive method to accurately identify genome-edited mutants by using DNA from insect exuviae. We compared the quantity and quality of genomic DNA from exuviae in five instar hoppers and found that the 1st instar exuviae had the highest DNA yield and content, while the 3rd instar exuviae had the best quality. Consensus genotypes were identified from genomic DNA of hoppers at different developmental stages in the same individuals. Moreover, we demonstrated that the amplification products from DNA extracted from locust exuviae are the consensus sequences with those from the hemolymph and foreleg pre-tarsus. Therefore, non-invasive samples provide the same genotyping results as minimally invasive and invasive samples of the same individuals. Furthermore, this identification method that uses genomic DNA from exuviae can be used for early screening of positive genome-edited individuals in each generation for adult crossing. In our study, the non-invasive identification method was not only simpler and provided results earlier than existing methods, but also had a better reproducibility and accuracy. This non-invasive identification approach using genomic DNA from exuviae can be adapted to meet the growing demand for genetic analysis and will find wide application in insect genome editing research.

[Genetic and clinical analysis of X-linked hypophosphatemic rickets]

Objective: To investigate the clinical and genetic features, and treatment of X-linked hypophosphatemic rickets (XLH). Methods: In this retrospective study, we reviewed the medical records of 25 pediatric patients with XLH who were admitted to Department of Endocrinology Genetics and Metabolism,Beijing Children's Hospital from January 2010 to January 2020. The clinical characteristics, PHEX gene variants, as well as clinical outcome of the patients were summarized. To analyze the correlation between genotype and phenotype, the patients were divided into different subgroups according to the location of the variants, including N-terminal-located vs. C-terminal-located variant, and Zn-binding domain exon 17 or 19 variant vs. non-exon 17 or 19 variant. The age at onset, height standard deviation score (HtSDS), intercondylar or intermalleolar distance, fasting serum phosphorus, and HtSDS and intercondylar or intermalleolar distance at the final follow-up were compared by rank sum test or t text. Results: Among the 25 children with XLH, 8 were boys and 17 were girls. The median age of onset was 1.2 (1.0, 1.8) years, and the median age of diagnosis was 2.5 (1.5, 4.3) years. The main clinical manifestations were abnormal gait and lower limb deformity. The HtSDS was -2.0(-3.2, -0.8), and the intercondylar or intermalleolar distance was 4.5 (3.0, 6.0) cm. The fasting serum phosphorus level was 0.8 (0.7, 0.9) mmol/L, while the serum alkaline phosphatase level was (721±41) U/L and the serum calcium level was (2.5±0.1) mmol/L. Three patients (12%) had parathyroid hormone levels above the upper limit of the normal range. Twenty-five patients (100%) showed radiographic changes of active rickets. Nephrocalcinosis was found in 2 cases (9%). Twenty-four different PHEX variations were detected in 25 patients, among whom 11 (44%) had not been reported previously. No hot spot variation was found. No statistical differences (all P>0.05) were identified in clinical features and outcomes either in comparing patients with N-terminal (21 cases) and C-terminal (4 cases) variants, or in comparing patients with variant located in exon 17 or 19 (4 cases) or not (21 cases). Twenty-four cases (96%) were treated regularly with phosphate supplements and active vitamin D. After 2.7 (1.6, 5.0) years of follow-up, clinical symptoms were relieved in 96% (24/25) of the patients. The HtSDS after treatment had no significant difference compared to that before treatment (-2.0(-3.2, -0.8) vs.-2.0(-2.8, -1.1),Z =-0.156, P>0.05), while the intercondylar or intermalleolar distance after treatment was significantly reduced compared to that before treatment (4.5(3.0, 6.0) vs. 1.5(0, 3.3) cm, Z =-3.043, P<0.05). Bone X-rays were reexamined in 17 cases after treatment, and radiographic signs of rickets were improved. Eighteen cases had secondary hyperparathyroidism and 7 cases had nephrocalcinosis. Conclusions: The main clinical manifestations of XLH are abnormal gait, lower limb deformity and short stature. A high proportion of novel variations of PHEX gene but no hot spot variation neither genotype-phenotype correlation are found. Regular treatment with phosphate supplements and active vitamin D can significantly improve the symptoms except for the height. However, the rate of adverse events including secondary hyperparathyroidism and nephrocalcinosis seems to be high.

[Diagnosis and follow-up of 2 cases of pediatric nephrogenic syndrome of inappropriate antidiuresis resulting from activating mutation in AVPR2 and literature review]

Objective: To analyze the clinical and genetic features, as well as the treatment outcomes of two boys with nephrogenic syndrome of inappropriate antidiuresis (NSIAD) caused by gain-of-function mutations in the V2 vasopressin receptor gene (AVPR2). Methods: The clinical manifestations, genetic testing, therapeutic interventions and the outcomes of two boys with NSIAD hospitalized in the Department of Endocrinology, Beijing Children's Hospital in April 2019 were reported. A literature search with "Nephrogenic syndrome of inappropriate antidiuresis" and "AVPR2 gene" as keywords was conducted at the China national knowledge infrastructure (CNKI), the Wanfang Data Knowledge Service Platform, PubMed and Springer Link up to May 2020. Relevant published articles were reviewed. Results: The two cases presented with chronic and severe hyponatremia with hypo-osmolality, inappropriately elevated urinary osmolality and urinary sodium levels. The onset age was 5.25-years and 2 months respectively. AVPR2 sequencing revealed a previously described hemizygous activating mutation (c.409C>T, p.R137C) in both of boys, each inherited the variant from their mother. Patient 1 limited fluid intake by himself in his daily life, intravenous and oral sodium supplementations showed no significant increase of serum sodium level. Oral furosemide increased the serum sodium level and maintained it within normal range. The serum sodium and potassium levels were in the normal range during the 1-year follow-up period with oral furosemide. The serum sodium level of Patient 2 increased with restricting fluid intake and with salt supplementation. However, after he experienced respiratory infection, the plasma sodium level decreased. Subsequently, oral anti-infection medicine and furosemide were applied. The serum sodium level increased two days later and remained at a normal range afterwards. The boy was 1 year old with normal growth. He stopped taking furosemide after 4 months while taking 1 gram of salt per day, the blood sodium level maintained at normal range. Literature search identified no reports in Chinese journals, whereas 50 publications were found in English journals. A total of 30 NSIAD probands were reported and 16 of those (53%) had childhood onset, most presented with seizures. The majority had a hotspot change at the nucleotide position of 409 in AVPR2. Nine cases had an amino acid change as R137C and five cases as R137L. Fluid restriction and oral urea intake were main treatment options, no report so far was found with oral furosemide treatment. Conclusions: NSIAD presented with hyponatremia without any other specific presentations. Genetic testing for variants in AVPR2 is helpful for early diagnosis and timely treatment. The first two cases of oral furosemide treatment were reported by the article which helped to maintain a normal serum sodium level after limiting fluid intake and supplementing sodium which showed limited effect.

Platelet-to-lymphocyte ratio is associated with prognosis in patients with coronavirus disease-19

Since December 2019, novel coronavirus infected pneumonia emerged in Wuhan city and rapidly spread throughout China. In severe novel coronavirus pneumonia cases, the number of platelets, their dynamic changes during the treatment, platelet-to-lymphocyte ratio (PLR) were a concern. We sought to describe the platelet feature of these cases. Single-center case series of the 30 hospitalized patients with confirmed coronavirus disease (COVID)-19 in Huizhou municipal central hospital from January 2020 to February 2020 were retrospectively analyzed. Demographic, clinical, blood routine results, other laboratory results, and treatment data were collected and analyzed. Outcomes of severe patients and nonsevere patients were compared. Univariate analysis showed that: age, platelet peaks, and PLR at peak platelet were the influencing factors in severe patients, multivariate analysis showed that the PLR value at peak platelet during treatment was an independent influencing factor in severe patients. The average hospitalization day of patients with platelet peaks during treatment was longer than those without platelet peaks (P < .05). The average age of patients with platelet peaks during treatment was older than those without platelet peaks (P < .05). The patients with significantly elevated platelets during treatment had longer average hospitalization days. And the higher PLR of patients during treatment had longer average hospitalization days. Single-center case series of the 30 hospitalized patients with confirmed COVID-19 in Huizhou Municipal Central Hospital, presumed that the number of platelets and their dynamic changes during the treatment may have a suggestion on the severity and prognosis of the disease. The patient with markedly elevated platelets and longer average hospitalization days may be related to the cytokine storm. The PLR of patients means the degree of cytokine storm, which might provide a new indicator in the monitoring in patients with COVID-19.

Serum prealbumin combined with Child-Pugh classification and MELD score for evaluation of liver function in patients with liver cirrhosis

AIM: To evaluate the clinical value of serum prealbumin (PA) in patients with liver cirrhosis.

METHODS: Three hundred and fifty-one patients diagnosed with cirrhosis at our hospital were retrospectively analyzed and followed for 1 year. Each patient's Child-Pugh classification and model for end-stage liver disease (MELD) score were calculated. Child-Pugh classification and MELD score were compared with serum PA combined with Child-Pugh classification and MELD score in evaluating liver function. Logistic regression analysis was used to evaluate survival at 1 year in patients with liver cirrhosis.

RESULTS: The patients were divided into three groups according to Child-Pugh classification: 111 patients in Child A group, 62 in Child B, and 178 in Child C. In the control group, Child A, Child B and Child C groups, serum PA levels were 261.5 ± 68.7, 152.6 ± 62.7, 70.7 ± 36.9 and 36.2 ± 13.1 mg/L, respectively, which had statistical differences among the four groups (P < 0.05 for all). Of 31 postoperative patients in the Child A group, the mean preoperative serum PA in 24 patients without peritoneal dropsy was 194.0 mg/L ± 56.1 mg/L, and the value in 7 patients with peritoneal dropsy was 123.1 mg/L ±35.4 mg/L (P < 0.05). MELD scores were calculated in 240 patients in the Child B and Child C groups. Compared with MELD score alone, serum PA combined with MELD score was better in predicting survival at 1 year (χ₂²-χ₁² = 8.229 > 3.84, P < 0.05).

CONCLUSION: Serum PA combined with Child-Pugh classification can predict peritoneal dropsy more efficiently. Serum PA combined with MELD score can predict survival results at 1 year more efficiently in patients with Child B and Child C diseases.

New advances in the use of serum prealbumin as an index of liver function

Serum prealbumin, mainly synthesized in the liver, can be used to assess the function of liver protein synthesis, reserve and nutritional status with many advantages such as convenience, accuracy and fewer interference factors; however, it is clinically used often as an independent factor, and there is little systematic, relevant and prospective research on it. Although serum prealbumin test has been used for a long time, many clinicians do not attach great importance to the characteristics of changes in serum prealbumin. In this paper, we will review new characteristics of biochemistry structure and function of serum prealbumin, and relevance between serum prealbumin and serum albumin, cholesterol, cholinesterase, total bile acids, prothrombin time, Child-Turcotte-Pugh, and model of end-stage liver stage.

Alterations in growth plate and articular cartilage morphology are associated with reduced SOX9 localization in the magnesium-deficient rat

Insufficient dietary magnesium (Mg) intake has been associated with low bone mass in humans,and recent basic science studies have indicated that this bone loss may be secondary to increased release of substance P and TNFc Much less is known about the effects of low Mg intake on cartilage. We have evaluated growth plate and articular cartilage in rats following a 6 month dietary Mg restriction. Histomorphometry demonstrated significantly decreased distal femur articular cartilage chondrocyte density and decreased tibial growth plate width in experimental animals compared to controls. Growth plates of Mg-restricted animals showed reduced chondrocyte column formation. Extracellular matrix of both articular cartilage and growth plates in experimental animals contained reduced amounts of proteoglycans. Immunolocalization of Sox9 was decreased in both articular and growth plate cartilage in experimental animals compared to controls, suggesting that reduced Mg intake causes cartilage changes that may be secondary to reduced levels of the SOX9 transcription factor.

The delayed genotoxic effect of N-nitroso N-propoxur insecticide in mammalian cells

The N-nitroso derivative of an extensively used insecticide, propoxur, consistently induced dose-responsive chromosome aberrations and sister-chromatid exchanges (SCEs) in Chinese hamster ovary (CHO-W8) cells. Further investigations indicated that post-treatment incubation with a regular 1.5-cell-cycle period did not offer an unbiased estimation of the genotoxicity of N-nitroso carbamate insecticides. The scale of chromosome aberration induction increased with extension of the post-treatment incubation period. Comparable phenomena were not found in CHO-AGT cells proficient for O(6)-methylguanine-DNA-methyltransferase. In CHO-W8 cells, pulsed-treatment of the insecticide in the 1st replication cycle showed higher SCE induction than in the 2nd cycle. Similar phenomenon was also found in SCE induced by N-nitroso derivatives from other carbamate insecticides including aldicarb, carbofuran and methomyl. Treated cells did not show significantly perturbed cell cycle progression until 12 h after treatment removal. Based on the above observations, the O(6)-methylguanine-DNA adduct is suggested to be the major lesion caused by the delayed genotoxic effect of N-methyl carbamate insecticides as described in this report.

Reduction of dietary magnesium by only 50% in the rat disrupts bone and mineral metabolism

INTRODUCTION

The objective of this study was to determine the effect of a moderate reduction of dietary magnesium [50% of nutrient requirement (50% NR)] on bone and mineral metabolism in the rat, and to explore possible mechanisms for the resultant reduced bone mass.

METHODS

Female rats were 6 weeks of age at the start of study. Serum magnesium (Mg), calcium (Ca), parathyroid hormone (PTH), 1,25(OH)(2)-vitamin D, alkaline phosphatase, osteocalcin, and pyridinoline were measured during the study at 3- and 6-month time points in control (dietary Mg of 100% NR) and Mg-deficient animals (dietary Mg at 50% NR). Femurs and tibias were also collected for mineral content analyses, micro-computerized tomography, histomorphometry, and immunohistochemical localization of substance P, TNFalpha, and IL-1beta at 3 and 6 months.

RESULTS

Although no significant change in serum Mg was observed, Mg deficiency developed, as assessed by the reduction in bone Mg content at the 3- and 6-month time points (0.69+/-0.05 and 0.62+/-0.04% ash, respectively, in the Mg depletion group compared to 0.74+/-0.04 and 0.67+/-0.04% ash, respectively, in the control group; p=0.0009). Hypercalcemia did not develop. Although serum Ca level remained in the normal range, it fell significantly with Mg depletion at 3 and 6 months (10.4+/-0.3 and 9.6+/-0.3 mg/dl, respectively, compared to 10.5+/-0.4 and 10.1+/-0.6 mg/dl, respectively, in the control group; p=0.0076). The fall in serum Ca in the Mg-depleted animals was associated with a fall in serum PTH concentration between 3 and 6 months (603+/-286 and 505+/-302 pg/ml, respectively, although it was still higher than the control). The serum 1,25(OH)(2)-vitamin D level was significantly lower in the Mg depletion group at 6 months (10.6+/-7.1 pg/ml) than in the control (23.5+/- 12.7 pg/ml) (p<0.01 by the t-test). In Mg-deficient animals, no difference was noted in markers of bone turnover. Trabecular bone mineral content gain was less over time in the distal femur with Mg deficiency at 3 and 6 months (0.028+/-0.005 and 0.038+/-0.007 g, respectively, compared to 0.027+/-0.004 and 0.048+/-0.006 g, respectively, in the control group; p<0.005). Histomorphometry at these time points demonstrated decreased trabecular bone volume (15.76+/-1.93 and 14.19+/-1.85%, respectively, compared to 19.24+/-3.10 and 17.30+/-2.59%, respectively, in the control group; p=0.001). Osteoclast number was also significantly increased with Mg depletion (9.07+/-1.21 and 13.84+/-2.06, respectively, compared to 7.02+/-1.89 and 10.47+/-1.33, respectively, in the control group; p=0.0003). Relative to the control, immunohistochemical staining intensity of the neurotransmitter substance P and of the cytokines TNFalpha and IL-1beta was increased in cells of the bone microenvironment in the Mg depletion group, suggesting that inflammatory cytokines may contribute to bone loss.

CONCLUSION

These data demonstrate that Mg intake of 50% NR in the rat causes a reduced bone mineral content and reduced volume of the distal femur. These changes may be related to altered PTH and 1,25(OH)(2)-vitamin D formation or action as well as to an increase release of substance P and the inflammatory cytokines TNFalpha and IL-1beta.

Modulation of intraocular pressure by unilateral and forced unilateral nostril breathing in young healthy human subjects

PURPOSE

To determine the effects of unilateral right/left nostril breathing (URNB/ULNB) and forced unilateral right/left nostril breathing (FURNB/FULNB) on intraocular pressure (IOP) and to examine the differences in the IOP during the various phases of nasal cycle.

METHODS

Young healthy volunteers of either sex aged between 19-24 years, participated in the sessions using URNB/ULNB (n = 52) and FURNB/FULNB (n = 28). The nostril dominance was calculated from signals recorded on the PowerLab equipment, representing pressure changes at the end of the nostrils during respiration. The IOP was measured with Tono-Pen. The subjects were divided into 4 groups viz. right nostril dominant (RND), left nostril dominant (LND), transitional right nostril dominant (TRND) and transitional left nostril dominant (TLND) groups. The IOP data 'before and after' URNB/ULNB or FURNB/FULNB were compared by using paired t-test. The baseline data of IOP between the groups were analysed by using independent samples t-test.

RESULTS

The URNB decreased the IOP in the LND and TLND (p < 0.01) and also in the RND (p < 0.05) groups but not significantly in the TRND group. The ULNB decreased the IOP in the RND group (p < 0.01) only. The FURNB significantly reduced the IOP (p < 0.05) only in the LND and RND groups. The FULNB decreased the IOP but not significantly. The baseline IOP did not differ significantly between the LND, RND, TLND and TRND groups.

CONCLUSION

The URNB/FURNB reduced the IOP, while ULNB/FULNB failed to increase the IOP significantly. It is suggested that the lowering of IOP by URNB indicated sympathetic stimulation.

Magnesium deficiency: effect on bone and mineral metabolism in the mouse

Insufficient dietary magnesium (Mg) intake has been associated in humans with low bone mass. Mg deficiency in the rat has suggested bone loss is due to increased bone resorption and/or inadequate bone formation during remodeling. The purpose of this study was to assess the effect of a low Mg diet on bone and mineral metabolism in the young and mature BALB/c mouse and explore the hypothesis that inflammatory cytokines may contribute to Mg deficiency-induced osteoporosis. Using an artificial diet, we induced targeted Mg depletion (0.002% Mg) with all other nutrients maintained at the normal level. In all Mg-depleted mice, hypomagnesemia developed and skeletal Mg content fell significantly. The serum Ca in Mg-deficient mice was higher than in control mice; however, serum PTH levels were not significantly different. Osteoprotegerin (OPG) in dosages that inhibit osteoclastic bone resorption did not prevent hypercalcemia in Mg-deficient animals. No significant difference in serum Ca was observed between groups when dietary Ca was reduced by 50%, suggesting that a compensatory increase in intestinal absorption might account for the hypercalcemia. Growth plate width decreased 33% in young Mg-deficient animals and chondrocyte columns decreased in number and length, suggesting that Mg deficiency reduced bone growth. Trabecular bone volume in the metaphysis of the tibia in these animals was decreased and osteoclast number was increased by 135%. Osteoblast number was significantly reduced. Immunohistochemistry revealed that substance P increased 230% and 200% in megakaryocytes and lymphocytes, respectively, after 1 day of Mg depletion. IL-1 increased by 140% in osteoclasts by day 3 and TNF alpha increased in osteoclasts by 120% and 500% in megakaryocytes on day 12. This study demonstrates a profound effect of Mg depletion on bone characterized by impaired bone growth, decreased osteoblast number, increased osteoclast number in young animals, and loss of trabecular bone with stimulation of cytokine activity in bone.

Separation of pure elemental and oxygen influenced signal in ELNES

The energy loss near edge structure (ELNES) of many elements is strongly influenced by the presence of oxygen or other elements at surfaces, grain boundaries, or in the bulk material. The presented investigation deals mainly with the influence of oxygen at the surface. A method for the separation of both, the pure bulk signal and the oxidized surface signal, was evaluated and tested on Al, Cu, Mg, and Si. A comparison of experimental data with ab initio bandstructure calculations and other proofs of the accuracy of ELNES separation are presented. Influences of error propagations were tested and are exemplarily given for Al and Si.

Genotoxic effects of triphenyltin acetate and triphenyltin hydroxide on mammalian cells in vitro and in vivo

Two organotin pesticides, triphenyltin acetate (TPTA) and triphenyltin hydroxide (TPTH), were evaluated for their ability to induce micronuclei (MN) and sister chromatid exchange (SCE) in vitro using cultured Chinese hamster ovary (CHO) cells and in vivo BALB/c mouse erythrocytes. Both pesticides induced a dose-dependent increase but only TPTH induced a significant increase in MN at the highest dose (150 ng/ml) tested in CHO cells. With adding S9 microsomal fractions, both pesticides induced a meaningful MN induction at 150 ng/ml and a dose-dependent significant increase in SCE. In vivo MN induction in erythrocytes was conducted by treating BALB/c mice orally or intraperitoneally with these pesticides either in a single or triple treatments. Oral gavage (p.o.) of TPTA resulted in a dose-related significant increase of MN induction in peripheral blood and of TPTH induced a significant increase in micronucleated reticulocyte (MNRETs) only in a single treatment. Intraperitoneal administration of TPTA or TPTH, however, resulted in meaningless random increases in MN though these increases might be attributable to toxic effects. The MNRETs levels in the treatment with both pesticides were independent to the sampling time. This study demonstrated that TPTA and TPTH was potential chromosome mutagens.

Preparation for TEM of layered samples with fragile microstructure and weak layer interface

The objective of this work was to prepare for transmission electron microscopy (TEM) a layered structure of materials with fragile microstructure. The samples consisted of two layers of different materials, silicon nitride and borosilicate glass, loosely bonded together. The low strength of the sample resulted in fragmentation during more conventional preparation. However, it was possible to prepare the fragments by mounting them in a titanium specimen carrier with aluminium strips as support. After grinding and polishing, a technique of low-angle ion milling was used to obtain electron beam transparent areas at the nitride/glass interface.

Altered pHi regulation in 3T3/CFTR clones and their chemotherapeutic drug-selected derivatives

Recently (L. Y. Wei, M. J. Stutts, M. M. Hoffman, and P. D. Roepe. Biophys. J. 69: 883-895, 1996), 3T3 cells overexpressing the cystic fibrosis transmembrane conductance regulator (CFTR) were found to exhibit chemotherapeutic drug resistance and other traits of multidrug resistant (MDR) cells. In the present work, NIH 3T3/CFTR clones were selected with either doxorubicin or vincristine in incremental fashion to generate series of stable MDR cell lines that exhibit increasing levels of drug resistance. Thus C3D6 (grown in the presence of 600 nM doxorubicin) was selected from C3D4 (grown in the presence of 400 nM doxorubicin), which was selected from C3D1 (grown in the presence of 100 nM doxorubicin), which was in turn selected from the original 3T3/CFTR clone C3 (M. J. Stutts, S. E. Gabriel, J. C. Olsen, J. T. Gatzy, T. L. O'Connell, E. M. Price, and R. C. Boucher. J. Biol. Chem. 268: 20653-20658, 1993), which was not grown in the presence of chemotherapeutic drug. A similar series was generated via selection with vincristine. In both series, as well as series derived from a different CFTR clone, initial low-level drug selection increases CFTR expression without promoting MDR 1 or multidrug resistance-associated protein expression. On continued selection at higher drug concentrations, CFTR mRNA levels decrease while MDR 1 mRNA levels concomitantly increase. At each incremental step of selection, intracellular pH (pHi) increases (e.g., pHi of C3D6 > C3D4 > C3D1 > C3). Cl-/HCO3- exchange activity is significantly reduced in the drug-selected derivatives overexpressing MDR 1 but not the parental CFTR clones. The apparent set point of Na+/H+ exchange activity is significantly lower for the non-drug-selected 3T3/CFTR clones, relative to controls, but it increases on initial selection with chemotherapeutic drug. Overexpression of MDR 1 in the higher-level selectants does not appear to further perturb apparent Na+/H+ exchange. These data further describe how CFTR and MDR proteins may affect pHi regulation.

Ultramicrotomy of powder material for TEM/STEM study

This paper summarizes methods conventionally used to prepare thin foil samples of powder materials for transmission electron microscopy (TEM) and introduces another variant, ultramicrotomy, for the preparation of TEM samples of industrial dust powder. The choice of ultramicrotoming in the present work was based on two features of this technique: (1) it can produce thin-sectioned specimens with a uniform thickness; (2) it can retain the original elemental distribution in phases of the sample during sectioning. Dust powder preparation and the sectioning procedure are described in this paper. The results of the method are illustrated by examples of TEM/STEM micrographs of industrial dust.

Assessment of the ability of propoxur, methomyl, and aldicarb, three carbamate insecticides, to induce micronuclei in vitro in cultured Chinese hamster ovary cells and in vivo in BALB/c mice

Three carbamate insecticides (propoxur, methomyl, and aldicarb) were evaluated for their ability to induce micronuclei (MN) in vitro using cultured Chinese hamster ovary (CHO) cells, and in vivo in mouse bone marrow erythrocytes. In vitro, all three insecticides induced a significant increase in micronucleated binucleate cells, which was generally both dose and sample time dependent. The in vivo studies involved treating male BALB/c mice by different routes, either once or on 3 consecutive days, followed by multiple or single sampling. Treatment by intraperitoneal injection or oral gavage induced a significant increase in micronucleated reticulocytes (MNRETs) in peripheral blood. For all three chemicals, the MN response depended on sample time and the number of treatments, while for aldicarb, the response depended also on the route of exposure. These positive results demonstrate that propoxur, methomyl, and aldicarb are capable of inducing structural and/or numerical chromosomal aberrations in mammalian cells either in vitro or in vivo. Furthermore, based on the results obtained, on optimal in vivo MN protocol for carbamate insecticides is a single treatment followed by blood sampling at 24 and 48 hr after treatment.

Altered drug translocation mediated by the MDR protein: direct, indirect, or both?

Overexpression of the MDR protein, or p-glycoprotein (p-GP), in cells leads to decreased initial rates of accumulation and altered intracellular retention of chemotherapeutic drugs and a variety of other compounds. Thus, increased expression of the protein is related to increased drug resistance. Since several homologues of the MDR protein (CRP, ItpGPA, PDR5, sapABCDF) are also involved in conferring drug resistance phenomena in microorganisms, elucidating the function of the MDR protein at a molecular level will have important general applications. Although MDR protein function has been studied for nearly 20 years, interpretation of most data is complicated by the drug-selection conditions used to create model MDR cell lines. Precisely what level of resistance to particular drugs is conferred by a given amount of MDR protein, as well as a variety of other critical issues, are not yet resolved. Data from a number of laboratories has been gathered in support of at least four different models for the MDR protein. One model is that the protein uses the energy released from ATP hydrolysis to directly translocate drugs out of cells in some fashion. Another is that MDR protein overexpression perturbs electrical membrane potential (delta psi) and/or intracellular pH (pHi) and thereby indirectly alters translocation and intracellular retention of hydrophobic drugs that are cationic, weakly basic, and/or that react with intracellular targets in a pHi or delta psi-dependent manner. A third model proposes that the protein alternates between drug pump and Cl- channel (or channel regulator) conformations, implying that both direct and indirect mechanisms of altered drug translocation may be catalyzed by MDR protein. A fourth is that the protein acts as an ATP channel. Our recent work has tested predictions of these models via kinetic analysis of drug transport and single-cell photometry analysis of pHi, delta psi, and volume regulation in novel MDR and CFTR transfectants that have not been exposed to chemotherapeutic drugs prior to analysis. This paper reviews these data and previous work from other laboratories, as well as relevant transport physiology concepts, and summarizes how they either support or contradict the different models for MDR protein function.

Are altered pHi and membrane potential in hu MDR 1 transfectants sufficient to cause MDR protein-mediated multidrug resistance?

Multidrug resistance (MDR) mediated by overexpression of the MDR protein (P-glycoprotein) has been associated with intracellular alkalinization, membrane depolarization, and other cellular alterations. However, virtually all MDR cell lines studied in detail have been created via protocols that involve growth on chemotherapeutic drugs, which can alter cells in many ways. Thus it is not clear which phenotypic alterations are explicitly due to MDR protein overexpression alone. To more precisely define the MDR phenotype mediated by hu MDR 1 protein, we co-transfected hu MDR 1 cDNA and a neomycin resistance marker into LR73 Chinese hamster ovary fibroblasts and selected stable G418 (geneticin) resistant transfectants. Several clones expressing different levels of hu MDR 1 protein were isolated. Unlike previous work with hu MDR 1 transfectants, the clones were not further selected with, or maintained on, chemotherapeutic drugs. These clones were analyzed for chemotherapeutic drug resistance, intracellular pH (pHi), membrane electrical potential (Vm), and stability of MDR 1 protein overexpression. LR73/hu MDR 1 clones exhibit elevated pHi and are depolarized, consistent with previous work with LR73/mu MDR 1 transfectants (Luz, J.G. L.Y. Wei, S. Basu, and P.D. Roepe. 1994. Biochemistry. 33:7239-7249). The extent of these perturbations is related to the level of hu MDR 1 protein that is expressed. Cytotoxicity experiments with untransfected LR73 cells with elevated pHi due to manipulating percent CO2 show that the pHi perturbations in the MDR 1 clones can account for much of the measured drug resistance. Membrane depolarization in the absence of MDR protein expression is also found to confer mild drug resistance, and we find that the pHi and Vm changes can conceivably account for the altered drug accumulation measured for representative clones. These data indicate that the MDR phenotype unequivocally mediated by MDR 1 protein overexpression alone can be fully explained by the perturbations in Vm and pHi that accompany this overexpression. In addition, MDR mediated by MDR protein overexpression alone differs significantly from that observed for MDR cell lines expressing similar levels of MDR protein but also exposed to chemotherapeutic drugs.

Overexpression of the cystic fibrosis transmembrane conductance regulator in NIH 3T3 cells lowers membrane potential and intracellular pH and confers a multidrug resistance phenotype

Because of the similarities between the cystic fibrosis transmembrane conductance regulator (CFTR) and multidrug resistance (MDR) proteins, recent observations of decreased plasma membrane electrical potential (delta psi) in cells overexpressing either MDR protein or the CFTR, and the effects of delta psi on passive diffusion of chemotherapeutic drugs, we have analyzed chemotherapeutic drug resistance for NIH 3T3 cells overexpressing different levels of functional CFTR. Three separate clones not previously exposed to chemotherapeutic drugs exhibit resistance to doxorubicin, vincristine, and colchicine that is similar to MDR transfectants not previously exposed to chemotherapeutic drugs. Two other clones expressing lower levels of CFTR are less resistant. As shown previously these clones exhibit decreased plasma membrane delta psi similar to MDR transfectants, but four of five exhibit mildly acidified intracellular pH in contrast to MDR transfectants, which are in general alkaline. Thus the MDR protein and CFTR-mediated MDR phenotypes are distinctly different. Selection of two separate CFTR clones on either doxorubicin or vincristine substantially increases the observed MDR and leads to increased CFTR (but not measurable MDR or MRP) mRNA expression. CFTR overexpressors also exhibit a decreased rate of 3H -vinblastine uptake. These data reveal a new and previously unrecognized consequence of CFTR expression, and are consistent with the hypothesis that membrane depolarization is an important determinant of tumor cell MDR.

Novel Cl(-)-dependent intracellular pH regulation in murine MDR 1 transfectants and potential implications

Previously [Luz et al. (1994) Biochemistry 33, 7239-7249], we determined that Cl(-)- and -HCO3-dependent pHi homeostasis was perturbed in multidrug resistant (MDR) cells created by transfecting LR73 Chinese hamster ovary fibroblasts with wild-type mu (murine) MDR 1 (Gros et al., 1991). Via single-cell photometry experiments performed under various conditions, we are now able to separate Na(+)-dependent and Na(+)-independent components of Cl-/-HCO3 exchange in the MDR transfectants and the parental LR73 cells. Cl(-)-dependent, Na(+)-independent reacidification of pHi, mediated by the anion exchanger 2 isoform in LR73 cells, is dramatically inhibited by mild overexpression of MDR protein. Analysis of H+ flux at different pHi shows that Cl(-)-dependent reacidification approaches 0.2 mM H+/s for LR73 cells at pHi = 8.0 but is at least 10-fold slower for MDR 1 transfectants that were never exposed to chemotherapeutics (EX4N7 cells). MDR 1 transfectants selected on the chemotherapeutic vinblastine (1-1 cells), which express approximately 10-fold more MDR protein relative to EX4N7 cells, exhibit similar behavior; however, alterations in Cl(-)-dependent pHi regulation are more severe. Hypotonic conditions, which have been shown to increase anomalous Cl- conductance in some cells overexpressing MDR protein (Valverde et al., 1992), are found to amplify the altered pHi homeostasis features in the primary transfectants that express lower levels of MDR protein such that they then mimic the behavior of the drug-selected cells that express substantially more MDR protein. Verapamil reverses the anomalous behavior.(ABSTRACT TRUNCATED AT 250 WORDS)

Low external pH and osmotic shock increase the expression of human MDR protein

We have studied the effects of extracellular pH (pHo) and osmotic strength on the expression of the human multidrug resistance (MDR) protein. Both lowered pHo and hypertonic shock increase the level of hu MDR protein 5-10-fold in membranes isolated from the human colon carcinoma cell lines SW620 and HCT15 and the human kidney carcinoma line SKRC-39. Increased protein expression is dependent on the duration of acid or osmotic shock and is reversed within several days when normal growth conditions are restored. Quantitative northern blot analysis with a hu MDR 1 specific probe reveals increased MDR mRNA in the acid and hypertonically shocked cells. Interestingly, we find a greater increase in mRNA levels for hypotonically shocked colon cells, without an apparent increase in protein levels. Overexpressing cells are found to retain less [3H]vinblastine relative to cells cultured under normal conditions, and they are resistant to the cytotoxic effects of doxorubicin, vinblastine, and colchicine, but not methotrexate. This resistance appears to be reversed by treatment with verapamil. In contrast, SW620 cells previously induced to overexpress MDR protein via the administration of differentiation agents [Mickley et al. (1989) J. Biol. Chem. 264, 18031-18040] did not exhibit decreased retention of [3H]vinblastine; thus low-pHo-induced overexpression of MDR protein in these cells may provide additional factors that promote the full expression of the MDR phenotype. These data may help to explain why many solid tumors (e.g., of colon and kidney origin) develop MDR prior to chemotherapy, since they usually grow under similar acidic conditions. These data also support the contention that MDR protein may play a role in intracellular pH and volume homeostasis.

Transfection of mu MDR 1 inhibits Na(+)-independent Cl-/-HCO3 exchange in Chinese hamster ovary cells

We have used single-cell photometry to measure intracellular pH (pHi) for several MDR cell lines constructed by stably transfecting LR73 chinese hamster ovary fibroblasts with mutant and wild type murine MDR 1 genes. In addition, plasma membrane electrical potential (delta psi) has been measured for the same cells by the K+/valinomycin null point titration method using the ratiometric styryl probe di-4-ANEPPS. Both the untransfected, parental cell line and a cell line expressing substantial mutant MDR 1 protein (K432R/K1074R) that is unable to confer the MDR phenotype are found to have delta psi > or = -40 (+/- 5) mV and pHi < or = 7.16 (+/- 0.03) units. In contrast, MDR cell lines constructed by transfecting wild type mu MDR 1 cDNA are found to exhibit delta psi from 15 to 19 mV lower and pHi from 0.13 to 0.34 units higher. A cell line that overexpresses crippled MDR protein (S941F) that is not resistant to colchicine or doxorubicin, but which is resistant to vinblastine [Gros, P., Dhir, R., Croop, J., & Talbot, F. (1991) Proc. Natl. Acad. Sci. U.S.A. 88, 7289-7293], exhibits elevated pHi and slightly elevated delta psi, relative to LR73. Northern and western blot analyses confirm the substantial overexpression of the mu MDR genes and proteins in these lines, as well as the mild overexpression of endogenous hamster p-GP mRNA in some lines. In general agreement with previous studies that examined myeloma cells overexpressing hu MDR 1 protein [Roepe, P.D., Wei, L.-Y., Cruz, J., & Carlson, D. (1993) Biochemistry 32, 11042-11056] we find that overexpression of wild type mu MDR 1 protein inhibits Cl(-)- and -HCO3-dependent pHi homeostasis. Via single-cell photometry studies we now conclude that this is due to inhibition of Na(+)-independent Cl-/-HCO3 exchange (strict anion exchange or AE). As concluded previously for other MDR cells, decreased AE activity is not due to decreased expression of the exchanger; in fact, again similar to previous work [Roepe et al. (1993) Biochemistry 32, 11042-11056], we find increased levels of AE mRNA in some MDR cell lines. Models that may explain these data that are also consistent with the known physiology of cells that endogenously express MDR protein are suggested. These data are consistent with a model for MDR protein function wherein overexpression of the protein decreases delta psi and/or elevates pHi via Cl(-)- and -HCO3-dependent mechanisms.

Lower electrical membrane potential and altered pHi homeostasis in multidrug-resistant (MDR) cells: further characterization of a series of MDR cell lines expressing different levels of P-glycoprotein

Recently [Roepe, P.D. (1992) Biochemistry 31, 12555-12564], increased steady-state levels of chemotherapeutic drug efflux from multidrug-resistant (MDR) myeloma cells were correlated with intracellular alkalinization. To better understand elevated pHi in MDR cells, Na(+)- and Cl-dependent recovery of pHi upon intracellular acid or alkaline shock has been examined for this same series of MDR cell lines. In agreement with another recent report [Boscoboinik, D., Gupta, R.S., & Epand, R.M. (1990) Br. J. Cancer 61, 568-572], we find that the rate of Na(+)-induced alkalinization after an intracellular acid shock is increased in the MDR cells, relative to the drug-sensitive parent. Interestingly, we also now find that mRNA encoding the human Na+/H+ exchanger (NHE) is overexpressed in these MDR cells, but the level of overexpression does not correlate with the relative drug resistance or steady-state pHi. It is also found that the efficiency of Cl(-)dependent reacidification of pHi, after an intracellular alkaline shock is reduced in the MDR cells. This effect appears to correlate with the relative expression of MDR protein, but not the relative expression of Cl-/HCO3- exchanger (AE), which we now find is also altered in the series of cells. Since elevated pHi will increase delta pH across the plasma membrane, we have also measured the electrical potential for these cells using three different methods. Most interestingly, the magnitude of the plasma membrane electrical potential (delta psi) decreases concomitant with increased expression of the MDR protein. Energy provided by increased delta pH compensates for the lowered delta psi, such that the total electrochemical membrane potential (delta mu H+) remains similar among the cells in this series (delta mu H+ = delta psi - Z delta pH). These data, along with other recent experiments that associated an increased Cl- conductance with the expression of MDR protein [Valverde, M., Diaz, M., Sepúlveda, F.V., Gill, D.R., Hyde, S.C., & Higgins, C.F. (1992) Nature 355, 830-833], are consistent with a model for MDR protein-mediated multidrug resistance that does not entail direct active transport of lipophilic drugs by the MDR protein.

Factors affecting zero background frequency of sister-chromatid exchange in mosquito cells

A background level of sister-chromatid exchange (SCE) is found in mammalian cells. However, in the somatic cells of Drosophila melanogaster, there was no spontaneous SCE if a minimum concentration of bromodeoxyuridine (BrdU) was used. In this communication we report that in a mosquito (Aedes albopictus) cell line (C6/36), some cells also have no background SCE (0-SCE). Subclones of high (44%) or low (12%) frequency of 0-SCE cells were obtained, but none of them contained 100% 0-SCE cells. Increasing frequency of SCE/cell concomitant with decreasing frequency of 0-SCE cells was observed by raising the BrdU concentration in the culture medium during the first cell cycle, culturing cells at lower density and depleting reduced glutathione (GSH) with buthionine sulfoximine. Since these mosquito cells contain much higher level of GSH than Chinese hamster ovary (CHO) cells, and feeding cells with BrdU increased GSH in mosquito cells but decreased GSH in CHO cells, we speculate that GSH may play a role in the low or non-existent background SCE and in the high resistance to many DNA damaging agents of mosquito cells.

Electronic diagnoser of arterial pulse

An electronic diagnoser of the arterial pulse has been designed to give three outputs: pulse amplitude, instantaneous pulse rate (IPR) and spectral energy ratios (SER) at 5 and 10 Hz. The information thus provided will be useful for diagnosing many kinds of disease in the human body.

Area utilization efficiency of a sloping heliostat system for solar concentration

Area utilization efficiency (AUE) is formulated for a sloping heliostat system facing any direction. The effects of slope shading, incidence factor, sun shading, and tower blocking by the mirrors are all taken into account. Our results show that annually averaged AUEs calculated for heliostat systems (1) increase with tower height at low slope angles but less rapidly at high slopes, (2) increase monotonically with slope angle and saturate at large slopes for systems facing due south, (3) reach a maximum at a certain slope for systems facing other directions than due south, and (4) drop sharply at slopes greater than a certain value for systems facing due east or west due to slope shading effect. The results are useful for solar energy collection on nonflat terrains.

General formula for the incidence factor of a solar heliostat receiver system

A general formula is derived for the effective incidence factor of an array of heliostat mirrors for solar power collection. The formula can be greatly simplified for arrays of high symmetry and offers quick computation of the performance of the array. It shows clearly how the mirror distribution and locations affect the overall performance and thus provide a useful guidance for the design of a solar heliostat receiver system.

Scientific advance in acupuncture

In this paper we present scientific advance in acupuncture based on electrical, neurophysiological, biochemical and therapeutic studies made inside and outside China since the early fifties. New modalities other than traditional needling techniques notably developed in Japan, France and Germany are described. For future prospects, efforts by making use of systems approach, field-body interaction, self-defense self-strategy and circadian rhythm are likely to produce great fruition in medicine. Possibilities of making advances in "three P's" medicine (preventive medicine, precision medicine and people medicine) by acupuncture are discussed.

Theoretical foundation of Chinese medicine: a modern interpretation

The theoretical foundation of Chinese medicine as laid down in Hwang Ti Nei Ching is presented and interpreted here in modern language and conception. Our attempt is to bring Chinese medicine in harmony with Western science. Three Yin-Yang laws are formulated based on I Ching and Nei Ching and are justified from physics, mathematics and biology. The Wu-Hsing dynamic model is explained on the basis of dynamic interactions rather than static elements. The Ching-Lo doctrine is stressed upon its apparent correlations with the autonomic nervous system. Finally, the Chi is taken to play a role in life as the fields (gravitational, magnetic, nuclear, etc.) do in the physical world.

Electronic conduction in lipid films with metal contacts

The electrical characteristics of lipid films with Au and Hg contacts were investigated. Our results indicate that the conduction is mainly electronic and is electrode limited. With gold biased negatively, the current-voltage characteristics of thin and thick films follow the equations: I = 4.367 exp [9.58(eV + 0.21)(1/2)]. [1 - exp (-eV/kT)]pA, and I = 3.424 exp [8.59(eV + 0.082)(1/2)][1 - exp (-eV/kT)]pA, respectively. For thick films, the conductivity is insensitive to thickness. By temperature and photoresponse measurements the interface barrier height is found to be 1.09 eV. In view of the possible structural disorders in the films, a model is proposed to explain our findings based on the theory of noncrystalline materials. According to this model, the band gap for the film is 2.016 eV and the density of localized states is near the Fermi level, 1.31 x 10(18) cm(-3) eV(-1). The results may be helpful in providing some insight into the speculated electronic conduction in biological membranes.

Dipole theory of heat production and absorption in nerve axon

EXACT FORMULAS ARE DERIVED FOR THE ENERGY CHANGE OF A DIPOLE SYSTEM WITH TWO ENERGY STATES (OR BANDS) IN A CHANGING FIELD IN TWO CASES: (a) no dipole flip-flop and (b) dipole flip-flop caused by stimulation. Based on these formulas, the positive and negative heats are calculated. The results are in good agreement with experiment in case b but are 60-180% larger in case a. Furthermore, the theory shows that the negative heat cannot be less than the positive heat in case a but can be either way in case b, the latter result being found prevalent in experiment. It is concluded that nerve excitation is most likely to involve dipole flip-flop at the membrane surface. The theory is consistent in the interpretations and correlations of the electrical, optical, and thermal effects observed in nerve axon.

Conduction mechanisms in Lillie's iron-wire model of nerve

Based on theory and experiment, we found that the conduction through the oxide film in Lillie's iron-wire model is dominated by Schottky emission at low fields (below 10(6) v/cm), by electron tunneling from trap to trap at intermediate fields and by direct tunneling (Fowler-Nordheim type) at higher fields (above 3 x 10(6) v/cm). The trap-to-trap tunneling is considered to give rise to the negative resistance and the fixed position of the current maximum as observed. Some of the nervelike properties of the Lillie's model are interpreted on this tunneling mechanism.

Role of surface dipoles on axon membrane

A physical model of nerve excitation and conduction is proposed based on the discovery of three new axon membrane properties: the negative fixed surface charge, the birefringence change, and the infrared emission.